[gmx-users] Alchemically Change 1-4 Interactions

[Eric Dybeck]

Hello All,

I am attempting to alchemically change my solid small-molecule system from
one forcefield to another using a series of linearly interpolated lambda
states. For the bonds, angles, and dihedrals, a 'State A' and 'State B' can
be specified in the topology file which will linearly change the parameters.

However, my initial force-field has 1-4 interactions *included*, and my
final force-field has 1-4 interactions *excluded*. How can I set this up
within the topology file? Is there a way to have [ pairs ] change from
state A to state B? Can I linearly change FudgeLJ and FudgeQQ? (The
intermolecular interactions dont need to change, as they are the same for
both force-fields).

Thanks,
-- 
Eric Dybeck
Ph.D. Candidate
Department of Chemical Engineering
University of Virginia
102 Engineers Way
Charlottesville, VA 22904-4741